NiTi心血管支架的疲劳断裂性能分析

Fatigue and fracture behavior of Nitinol cardiovascular stents

目的对NiTi合金心血管支架进行疲劳寿命的预测研究。方法采用疲劳断裂的有限元分析方法,建立了三维空间NiTi心血管支架结构的模型,并分析了在生理脉动循环载荷作用下的心血管支架结构。结果有限元分析发现支架结构结点附近区域的正应力大、疲劳寿命低、损伤大;同时,支架结构的疲劳寿命预测发现,用结构表面进行氮化、喷丸硬化等方法处理的支架疲劳寿命较高。相关的实验结果显示疲劳裂纹或断裂总是发生在支架结点附近区域。结论生理载荷下的模拟结果与相关的实验结果相吻合,最终为心血管支架结构的安全性指导和设计提供了理论依据。

Objective To carry out analysis on the fatigue lifetime prediction of nitinol cardiovascular stents.Meth-od By using the finite element method of fatigure fracture,the three-dimensional nitinol cardiovascular stents were established to analyze the structure of cardiovascular stents under a physiological pulsating cyclic loading.Results Great normal stress,low fatigue life and serious fatigue damage were found to be located near the stents’knots,and stents with nitrided surface or shot peened surface were likely to have a longer fatigue life.During miniature fatigue testing,early fatigue cracks or fractures were always formed at locations near stents’ knots.Conclusions The simulating results under the physiological loading are matched with related experimen-tal results,which provide a theoretical basis for the reliability and design of the cardiovascular stents.